We have learned a great deal about borderline personality disorder. It is a moderately heritable condition that, when precipitated by environmental stress, generally has its onset in late adolescence or early adulthood. Although long thought to be stable and enduring over time, we now know that, as defined in DSM-IV-TR (and DSM-5, section II), borderline personality disorder demonstrates quite high rates of remission over time. In spite of high rates of diagnostic remission, however, inherent pathological traits and impaired levels of social, interpersonal, and occupational functioning remain relatively persistent.